Granted, I have never worked with a database the size of Github, so I've never had to deal with sharding issues. But, even though foreign keys can be a PITA in

Granted, I have never worked with a database the size of Github, so I've never had to deal with sharding issues. But, even though foreign keys can be a PITA in some situations, I prefer the DBMS to do it for me than rely on the application. Foreign keys have always kept my back. I've been burned a few times when they weren't used.